package com.learn.acm.bytedance;


import org.junit.jupiter.api.Test;

/**
 *
 * 21. 合并两个有序链表
 * 将两个升序链表合并为一个新的 升序 链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的。
 *
 *
 *
 * 示例：
 *
 * 输入：1->2->4, 1->3->4
 * 输出：1->1->2->3->4->4
 * @author zhongshitao
 * @date 2020/9/22 3:36 下午
 */
public class Solution21 {
















    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        if (null == l1) {
            return l2;
        } else if (l2 == null) {
            return l1;
        }else if (l1.val <= l2.val) {
            l1.next = mergeTwoLists(l1.next,l2);
            return l1;
        } else {
            l2.next = mergeTwoLists(l1,l2.next);
            return l2;
        }
    }




    /**
     * Definition for singly-linked list.
     * public class ListNode {
     *     int val;
     *     ListNode next;
     *     ListNode() {}
     *     ListNode(int val) { this.val = val; }
     *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
     * }
     */
    @Test
    public void testList(){
        ListNode l11 = new ListNode(1);
        ListNode l12 = new ListNode(2);
        ListNode l13 = new ListNode(3);
        ListNode l21 = new ListNode(1);
        ListNode l22 = new ListNode(3);
        ListNode l23 = new ListNode(4);
        l11.next = l12;
        l12.next = l13;
        l21.next = l22;
        l22.next = l23;
        mergeTwoLists(l11,l21);
    }



    class ListNode {

        int val;

        ListNode next;
        ListNode() {

        }
        ListNode(int val) {
            this.val = val;
        }
        ListNode(int val, ListNode next) {
            this.val = val;
            this.next = next;
        }
    }
}
